There has been proposed a combine configured to effect a weight measurement or a moisture measurement on grains stored in a grain tank and then to output the result as harvest information of harvested grains. For instance, in the case of a combine disclosed in Patent Document 1, the combine includes a moisture measurement device configured to take in some of grains supplied to a grain tank and to measure a moisture amount thereof and a load cell configured to detect a load of the grain tank. During a harvesting travel of this combine, calculation of a reaping area from a travel speed, a travel time and a reaping width and calculation of increase (increment) in a grain weight per this reaping area are effected in repetition, whereby a yield distribution per unit segment of a field is outputted. However, if such grain weight increase is measured from the load of the grain tank, as the weight of grains is small as compared with the weight of the grain tank, significant cost will be required for realization of a measurement mechanism capable of accurate measurement of small increment in the grain weight. Without accurate measurement of small increment in the grain weight, it will become difficult to evaluate harvesting failure in a very small segment of the field, due to such factors as irregularities of exposure to sunshine, fertilization, etc.
Patent Document 2 discloses a combine having a yield detection device configured to measure yield of grains per unit time for the purpose of adjustment control of a sorting device. This yield detection device consists of a cylinder body, a shutter for opening and closing a lower opening of the cylinder body and a pressure sensor provided inside the cylinder body and the yield detection device is configured such that a time until accumulation of grains up to the position of the sensor is measured and then based on this measured time, a yield per unit time of the grain is determined. With this combine, the sorting device is controlled merely such that the greater the grain volume per unit time passing this sorting device, the greater the processing amount of the sorting device. As such, no consideration is given to such factor as a travel speed of the combine, which factor causes variation in the yield per unit time, irrespectively of e.g. growth condition of grain culm (ripening state of grains).